铬与健康

对铬与人体健康的关系进行了综述，主要内容包括：三价铬的作用、六价铬的作用和环境中的铬。     

铬与人体健康

介绍了铬的生理功能,指出三价铬是人体必需的微量元素,六价铬则是严重危害人体健康的有害元素,必须适量补铬和严防六价铬的中毒,才能维持人体健康。     

离子液体分散液液微萃取-石墨炉原子吸收光谱法测定尿中铬

<正>铬是人体必需的微量元素之一,铬及其化合物可通过消化道、皮肤及黏膜进入人体,参与糖类、脂肪及蛋白质的代谢,但过多的铬进入人体会对人体健康造成危害。铬的开采、冶炼、铬盐的制造、电镀、金属加工、制革、油漆、颜料和印染等工业很容易引起相关职业人员铬中毒。铬中毒可导致过敏性哮     

二苯碳酰二肼光度法测定微量铬的改进

正以六价铬和三价铬价态存在的铬,在地壳中的含量排序稍靠前,属于自然界中分布较普遍的化学元素之一。其中三价铬参与协作生物体内葡萄糖平衡及脂肪、蛋白质的代谢作用,是人体新陈代谢必不可少的微量元素,但人体或动植物摄入过多的三价铬会对机体产生伤害;毒性较大、对人体表皮肌肤有刺激、有高致癌特性的六价铬更易被人体所吸收,在体内产生蓄积,污染环境又影响人体健康,因此铬是环境监测中的重要监控项目。目前,测定总铬含量     

乳浊液直接进样石墨炉原子吸收光谱法测定牛奶中的铬

"皮鞋奶"事件、"毒胶囊"事件将"铬"推入人们的视线,一时间人们"谈铬色变"。铬(Ⅲ)和铬(Ⅵ)与人体健康密切相关,其中铬(Ⅲ)是人体必需的微量元素,是机体中的葡萄糖耐量因子的重要组成部分,也参与脂质代谢调节,而铬(Ⅵ)有很强的生物毒性,容易进入人体细胞,对肝脏、肾等内脏器官和脱氧核糖核酸(DNA)造成损伤,在人体内蓄积具有致癌性并可能诱发基因突变[1]。牛奶是现代家庭饮食中常见的营养食品,但是由于生态环境受到工业污     

高效液相色谱-电感耦合等离子体质谱法测定玩具材料中六价铬

正我国是世界最大的玩具出口国,同时也是对欧盟出口玩具的大国。玩具中有害重金属元素会影响孩子的健康[1]。自然界中的铬具有不同的形态,主要是以三价铬[Cr(Ⅲ)]和六价铬[Cr(Ⅵ)]的形式存在。三价铬是人体维持健康的微量元素[2],Cr(Ⅵ)则具有较大毒性。美国环境保护局将Cr(Ⅵ)确定为17种高度危险的毒性物质之一。因     

用焦亚硫酸钠处理废水中铬

铬是环境中的一种主要污染物，铬的毒性与其存在的状态有极大的关系，不同价态的含铬物质对生物体和人体的危害大不相同。六价铬是一种致癌物质，对它的处理及测定有着重要的意义。     

电感耦合等离子体质谱法测定血浆和血清中12种微量元素

正人体内微量元素包括铁、锰、铜、锌、锶、硒等,其水平与人体健康的关系为当今生命科学研究中不可或缺的一部分,微量元素参与蛋白质结构,并通过与蛋白质和其他有机基团结合参与酶、激素和维生素等生物大分子的合成,微量元素代谢失衡会发生一系列病理改变并导致最终疾病~([1-2])。锌、铬、钒作为人体必需和可能必需微量元素之一,与糖尿病之间具有高度相关性~([3]),硒元素被认为是免疫系统中的抗癌元素,能够杀死肿瘤细胞,将疾病对人体的健康     

HPLC-ICP-MS联用技术应用于海产品中铬形态的分析

铬的工业用途很广,主要有金属加工、电镀、制革行业,这些行业排放的废水中的铬在水生生物体内富集~([1]),对海产品的质量带来巨大影响,损害人们的健康.环境中主要存在两种铬的形态,维持人体生命的必须元素Cr(Ⅲ)和具有高毒、强致癌性的Cr(Ⅵ)~([2]).因此,仅测定海产品中铬的总量已不能满足人们的需要,测定铬的形态十分有必要.     

稀土的人体健康效应

论述了稀土的人体健康效应及与疾病的关系，包括：人体的稀土来源，稀土污染对人体健康的影响和稀土含量异常与人体疾病的关系。     

New Chromium on Silica Gel Catalysts with very high activity for the polymerization of ethylene

Together with the known chromium (II)/silica gel catalyst (Phillips catalyst) for the polymerization of ethylene, two new ones have been investigated. It was found that a chromium(II)-“repoly” catalyst (prepared by short reaction of the chromium(II)/silica gel with ethylene at temperatures between 100 and 225°C) and a chromium(III)/silica gel catalyst have up to hundred times higher activity than the chromium(II) one. Activation energies were calculated as 54.6, 49.6 and 43.8 kJ per mol, respectively. The number of active sites was determined by measuring the integrated absorbance of the C? H and C?O stretching vibrations of the polymer. At low chromium concentration (0.056%) roughly 50% of all chromium was catalytically active in the case of chromium(II) and chromium(III) on silica gel. For the chromium(II)-“repoly” catalyst all chromium atoms can be active. The turnover numbers for the polymerization at 20°C were calculated as 0.1 (chromium(II)), 7.5 (chromium(II)-“repoly”) and 20 (sec^?1 atm^?1) (chromium(III)).     

Quantification of total chromium and hexavalent chromium in UHT milk by ETAAS

Procedures for the quantification of total chromium and hexavalent chromium in UHT milk samples are presented. Total chromium was determined directly in milk with the addition of a surfactant and a mixture of Pd and Mg as a chemical modifier. For the selective separation of hexavalent chromium, the sample pre-treatment consisted in precipitation of proteins and elution of the supernatant through a Chromabond NH2 column. The metal was eluted with nitric acid. Both total chromium and hexavalent chromium were evaluated by atomic absorption spectrometry with electrothermal atomization using the same instrumental conditions. The detection limits were 0.2 and 0.15 microgram l-1 for total chromium and hexavalent chromium, respectively. The linearity ranges under the optimized conditions were 0.2-20 and 0.15-50 micrograms l-1. For total chromium the precision was 4.9 and 5.7% for the analytical and the over-all procedure, respectively, and for hexavalent chromium 4.3 and 4.9%, respectively. The validation of both procedures was performed by the standard additions method and the recoveries were higher than 93% in all cases. For total chromium, a certified reference material was also used to validate the methodology. The methods were applied to the determination of total chromium and hexavalent chromium in 60 UHT milk samples.     

中子活化法研究富铬酵母中铬的含量和分布

利用中子活化法测定了富铬酵母细胞中的生物活性物质、细胞壁以及原隆质体中的铬的含量。铬通过细胞壁进入细胞后,８０％的铬存在于细胞的原生质体内;富铬酵母中的铬主要以生物活性物质的形式存在。表明无机铬化合物在富铬酵母细胞的培养过程中,被酵母细胞吸收,并转化成有机铬状态。     

Asymmetric synthesis of axially chiral biaryls: inversion of planar chirality vs axial isomerization and functionalization at the side chain of biaryl chromium complexes

Axially chiral syn-biaryl chromium complexes having a coordinating heteroatom substituent at the benzylic position gave anti-biaryl chromium complexes 5 with inversion of the planar chirality by heating in a nonaromatic solvent, while syn-biaryl chromium complexes with an o-methyl or formyl substituent afforded axially isomerized anti-biaryl chromium complexes under heating in an aromatic solvent. syn-biaryl and both enantiomeric anti-biaryl chromium complexes with the o-formyl group were stereoselectively prepared from an identical planar chiral arene chromium complex as chiral source. The formyl group of the axially chiral chromium complexes was functionalized by radical cyclization and beta-lactam formation, and hetero-Diels-Alder reaction.     

The determination of chromium species in natural waters

A method for the determination of chromium species has been developed and successfully applied to both fresh and sea water samples. The method utilizes pre-concentration of total chromium, chromium(ni) and particulate chromium at natural pH with accurate and precise analysis by a single flameless atomic absorption procedure. A minimal blank allows for a reliable detection limit of 0.02 nM, which is sufficient for most natural waters with chromium concentrations in the range 0.01–10 nM. Immediate shipboard preconcentration of the samples minimizes storage problems. The method is simple and rapid; 20 samples can be analysed in duplicate for total chromium, chromium(III) and particulate chromium in one day with routinely available reagents and equipment.     

Speciation Determination of Chromium(VI) and Chromium(III) in Soil Samples after Cloud Point Extraction

Abstract

To measure the different activity of chromium(VI) and chromium(III) in soil samples, chromium(VI) and total chromium (CrVI + CrIII) was extracted by KCl extracting agent and alkali fusion, respectively. Cloud point extraction (CPE) for speciation determination of chromium with double-slotted quartz tube atom trap–flame atomic absorption spectrometry (STAT-FAAS) was developed. Preconcentration of chromium(VI) and total chromium in different pH solutions was achieved by CPE, with ammonium pyrrolidine dithiocarbamate (APDC) as the chelating agent and Triton X-114 as the cloud point extractant. The conditions of CPE and determination were studied. Under the optimal conditions, the enrichment factor was 50 for chromium from the initial 100-mL sample solution to the final 2-mL determined solution. Compared to the FAAS method, the sensitivity was improved seven-fold for chromium by the STAT-FAAS method. The limit of detection was 0.082 µg/L for chromium.     

Elemental speciation for chromium in chromium picolinate products

Chromium picolinate products have been examined for different forms of chromium, using chromatographic separation and inductively coupled plasma mass spectrometric detection. The brands we evaluated contained no detectable amount of elemental chromium(VI), the toxic form. Since chromium picolinate might have other chromium forms as impurities, different products may contain different forms of chromium species. Compared with ion-exchange, reversed-phase chromatography showed excellent chromium recovery based on the amount stated on the product label.     

The determination of chromium in biological materials by atomic absorption spectroscopy

Biological samples were mineralized with a mixture of nitric, sulfuric, and perchloric acids. The chromium was oxidized to chromium(VI) followed by extraction into methyl isobutyl ketone in the cold. The ketone extract was aspirated into a fuel-rich hydrogen-air flame, and the absorption recorded using the 357.9 nm line of chromium. The limit of detection for chromium was found to be 10 p.p.b. Tissue chromium levels of normal albino rats were determined. Increased chromium values were observed for animals maintained on a high chromium diet compared to those fed a deficient diet.     

Chemical speciation of chromium in sea water: Part 3. The determination of chromium species

A method for the determination of chromium(III), chromium(VI) and organicallybound chromium in sea water is reported. It is confirmed that sea water contains about 9 × 10^-9 M dissolved chromium. This is shown to be divided as ca. 15% inorganic Cr(III), ca. 25% inorganic Cr(VI) and ca. 60% organically-bound chromium. It is suggested that the inconsistency of earlier results on the dominant chromium species and its concentration in sea water is largely due to the fact that organically bound chromium species were not considered.     

Quantitative analysis of chromium(V) by EPR spectroscopy

A procedure to accurately quantitate chromium(V) in environmental and medicinal chemistry samples was developed using electron paramagnetic resonance spectroscopy (EPRS) as the method of detection. It was found to have an error in the order of +/-10% and a detection limit of 0.010 mM (0.5 mg l(-1)) chromium(V). The method has been used to quantitate the formation of chromium(V) in the interaction of chromium(VI) with fulvic acid and a simple model of this acid, viz, 1.2-dihydroxybenzene. Analysis of solutions obtained from the reaction of 1,2-dihydroxybenzene with chromium(VI) demonstrated that even when the organic substrate was present in a 182-fold excess, the maximum chromium(V) concentration attained represented just 1.44% of the initial chromium(VI). Reactions between chromium(VI) and fulvic acid yielded similar results. It was therefore concluded that at background environmental concentrations of chromium and fulvic acid, the production of chromium(V) is insignificant, however, its possible importance in contaminated systems cannot be disregarded on this basis alone. The method for quantitative analysis reported in this paper should be an invaluable tool for investigations into the significance of chromium(V) in the toxicological mechanism of chromium(VI) and its role as a mutagenic agent.